How can I set a C/C++ memory watchpoint in vscode?

Question

In gdb I can type watch &variable, then continue and gdb will break whenever something writes to that address.

I am using vscode to debug and want to do the same thing (This is different from the watch window, which will only show variable values after a breakpoint has been hit). Is it possible?

I can manually add a breakpoint by clicking the '+' and enter &variable but it never becomes active and says the module has yet to be loaded. I've tried manually entering -exec watch &variable in the debugger console window, but after continuing execution with the play button it hangs (vscode thinks the program is running again but it's not).

There are some github issues for this but they're closed without reason:

• https://github.com/microsoft/vscode/issues/55931
• https://github.com/microsoft/vscode/issues/47117
• https://github.com/microsoft/vscode-debugadapter-node/issues/38

Answer 1

I had luck watching on an address. For example, if my target variable was at address 0xb79b90, I would execute -exec watch *0xb79b90 in the gdb terminal. Then I'd double check it was added as a hardware watchpoint with -exec info watch.

After continuing execution, the debugger would halt with an exception once the watchpoint is hit. vscode would display the line after the value was changed. I could then continue from there if necessary.